This invention relates to a shield for a glove box having radioactive material therein. In more detail, the invention relates to a sandwich arrangement of several flaps which allows easy ingress into the glove box and egress out of the glove box while at the same time providing a substantial barrier to radioactivity.
Considerable plutonium handling is done within glove boxes in order to protect the handler. Most radioactive doses from processing plutonium in glove boxes is the result of low energy photons streaming at the glove box portholes. These photons are mostly 13-21 keV L x-rays from plutonium and 60 keV gamma rays from americium 241. The glove box porthole should be closed with a radiation absorbent or impervious material when the glove box is not in use in order to reduce the radiation dose delivered to workers and attending personnel. One method available in the prior art is to provide cover plates which frictionally fit over the glove box porthole. The problem with these cover plates is that the workers must remove these plates to obtain access to the glove box interior and then leave them off because they interfere with the work process. Seldom are these plates replaced when the workers are finished with the glove box, thereby leaving open portholes with the attendant radiation streaming.
Ideally, a glove box porthole shield will allow easy ingress and egress for the worker while at the same time providing a substantially impervious shield to the particular radiation present in the glove box. The shield must be altered to accommodate various energy level radiation.
Representative prior art in the field is disclosed in the Landy U.S. Pat. No. 4,089,571 issued May 16, 1978 which discloses a glove box port and insert therefor which is contained within a glove having a sleeve connected to the periphery of the glove box port. The Landy device does not overcome the problem previously discussed since the operator still has to replace the insert after he is finished working within the glove box, and if he forgets to replace the insert, radioactive streaming will expose the attendant personnel to radiation hazard. The Dickson et al. U.S. Pat. No. 2,708,927 issued May 24, 1955 discloses an incubator for infants having a circular port resiliently flexible diaphragm closures within the port. A device of this type was tried as a radiation shield but was found to be unsatisfactory since the individual parts of the diaphragm often did not completely close, thereby permitting substantial radiation streaming to occur. The Lennard U.S. Pat. No. 2,803,370 issued August 20, 1957 discloses yet another closure device for housings using a protective atmosphere. The Lennard patent discloses a sandwich of rubber disks each having radial slits therein which intersect at the points spaced from the center of the disks. Abutting disks have intersection points removed from one another to insure complete closure.